Dielectric composition of halogenated aromatic hydrocarbon and organic antimony compound as a corrosion inhibitor



Aug. 28, 1951 R. JENKINS I 2,566,208

DIELECTRIC COMPOSITION OF HALOGENATED AROMATIC HYDROCARBON AND ORGANIC ANTIMONY COMPOUND AS A CORROSION INHIBITOR Filed Oct. 13, 1948 DIELECTRIC METAL CONTAINING HALOGENATED AROMATIC COMPOUND AND AN ORGANIC ANTIMONY COMPOUND AS CORROSION INHIBITOR I FIG 4 Infill/51111101171011 METAL FOIL PAPER IMPREGNATED WITH HALOGENATED AROMATIC COMPOLND AND A ()SPCEQIH EFJARNTIMONY COMPOUND AS CORROSION RusseII L. Jenkins XNVENTOR.

Patented Aug. 28, 1951 DIELECTRIC COMPOSITION OF HALOGEN- ATED AROMATIC HYDROCARBON AND ORGANIC ANTIMONY COMPOUND AS A CORROSION INHIBITOR Russell L. Jenkins, Anniston, Ala., assignor to Monsanto Chemical company st. Louis, Mo., a corporation of Delaware Application October 13, 1948, Serial No. 54,258

16 Claims. (Cl.'252-63.5)

The present invention relates to novel compositions of matter comprising halogenated organic materials and an organic antimony compound as a scavenging or corrosion inhibiting agent More specifically, the invention relates to apparatus, particularly electrical apparatus such as capacitors, transformers, circuit breakers, cables and the like containing the above compositions.

Halogenated organic compounds, more particularly halogenated aromatic compounds such as chlorinated biphenyl and chlorinated naph thalene are highly useful electrical insulating materials because of their high dielectric constants, thermal stability, resistance to oxidation, nonflammability and other valuable properties. How ever, it has been found that when exposed to elevated temperatures and/or high voltages, they partially decompose liberating hydrogen halides which have an exceedingly deleterious action on the paper insulation and metal parts of electrical apparatus.

For example, in transformers, circuit breakers and other electrical devices in which arcing occurs, the development of hydrogen halides as a result of the above decomposition presents a serious problem as they decrease the dielectric strength of the composition containing same and cause considerable damage by attacking paper insulation and corroding metal parts of the apparatus in which the composition is used. The undesirable efiect of the above decomposition is further manifested when the above halogenated organic compounds are used as capacitor impregnants. Thus, under high operating temperatures and direct current voltages, capacitors impregnated therewith undergo a characteristic type of deterioration which results inan ever increasing leakage current, a short capacitor life, visible localized decomposition of the dielectric and corrosion of the electrodes. Moreover, in the case of capacitors operating on alternating current, the decomposition sometimes results in an excessive increase in power factor of the dielectric material.

It is, therefore, the object of the present invention to provide new compositions of matter containing halogenated organic compounds wherein the above objectionable properties are either completely eliminated or substantially reduced.

An additional object is to provide transform ers, capacitors, circuit breakers, cables and the like containing halogenated organic compounds'in combination with acOllOSiOIl inhibitor or scav enger whereby the deleterious-action ofhydrogen halides on the paper insulation and metal parts thereof is eliminated or materiallyreduced.

Another object is to providea capacitor impregnant containing halogenated organic compounds and a corrosion inhibitor or scavenger whereby the deleterious eifect of hydrogen halides on the electrodes and paper insulation of capacitorsis substantially reduced or completely eliminated with the result that the capacitorhas a longer useful life and greater dielectricstabilitythan similar capacitors not containingthe corrosion inhibitor.

A further object is to provide the celluloslc insulation in transformers containing liquid halogenated organic compounds with .protection against rapid destruction by hydrogen halides evolved as the result of a minor arcwithin the transformer, thus permitting complete repairof the assembly by rapid replacement-or :removal of the particular part that gave rise to thearc and thereb avoiding destruction of .the; entire paper insulation of the transformer with 'a con sequent high cost of repair.

A still further object is 'to provide switches, cables and the like containing halogenated organic compounds and a corrosion inhibitor or scavenger Which practically eliminates the rusting-and corrosion normally accompanying the use of such devices filled with halogenated organic compounds per se.

Other objects and advantages of the -present invention will become apparent to'those-skilled in the art as the description proceeds.

I have discovered that halogen-decomposition products can be rendered substantially innocuous and the above objectives accomplished if, in accordance with the present invention, the halogenated organic compound to be protected -is associated with an organicantimonycompound selected'from the groups definedby the following general formulae:

wherein R representsan organic :radical, ru represents integers corresponding to then-valence .of antimony, X represents halide, oxide, sulfide, cyanide, thiocyanate, acetate, (benzoate, succinate, oxalate, tartrate and equivalent inorganic and/or organic radicals, n is selected from th group of values consisting of 0, 1, 2, 3-and 4 and y represents an integer selected from the values 2sand'4.

The above general formulae include com= pounds in which R represents aliphatic, .aromatic, alicyclic or heterocyclic groups per se .or various combinations of these .groups, with or without various substituents suchas chloride,

bromide, fluoride, carboxyl, hydroxy, sulfide or amino radicals.

Specific examples of organic antimony compounds of the type defined by the general formulae are trilauryl stibine; triphenyl stibine; tricyclohexyl stibine; tri-2,5-xylyl stibine; tri 2,4-xylyl stibine; tri-a-naphthyl stibine; trinaphthyl stibine oxide; tri-p-anisyl stibine; trip-phenetyl stibine; tri-xenyl stibine; lauryl diphenyl stibine; di-xenyl benzyl stibine; di-otolyl-p-tolyl stibine; diethyl phenyl stibine; cyclopentamethylene phenyl stibine; cyclo-tetramethylene phenyl stibine; tri-(p-chlorophenyl) stibine diiodide; tri naphthyl stibine dichloride; ethyl diphenyl stibine; tri (p-chlorophenyl) stibine; tri-o-tolyl stibine; ethyl dicyclohexyl stibine; triphenyl stibine dichloride; triphenyl stibine oxide; triphenyl stibine sulfide; triphenyl stibine cyanide; triphenyl stibine thiocyanate; tribenzyl stibine dichloride; tribenzyl stibine oxide; tri-camphoryl stibine dichloride; diphenyl stibine chloride; di-p tolyl stibine chloride; ptolyl stibine dichloride; phenyl stibine dichloride; phenyl stibine tetrachloride; diphenyl stibine trichloride; di-p-tolyl stibine trichloride; phenyl trimethyl stibine chloride; tri-a-thienyl stibine; tri-o (p-chlorophenyl) stibine oxide; tri a. thienyl stibine dichloride; triphenyl stibine dibenzoate; diphenyl stibine acetate; di-(p-bromophenyl) stibine acetate; triphenyl stibine diacetate; tria thienyl stibine dibenzoate; tetraphenyl distibine; tetra p-tolyl distibine; tetra p brom phenyl distibine; m m diamino, pp dihydroxy stibino benzene and diphenyl stibilne. Of these compounds, tri a thienyl stibine is preferred as it exhibits outstanding properties from the standpoint of inhibiting the deleterious action of halogen decomposition products on metal and organic insulation materials.

For a more complete understanding of V the present invention, reference is made to the accompanying drawings and the experimental data hereinafter presented in the specific examples.

Figure ,1 is a front elevation partly in section of a transformer; Figure 2 illustrates a switch in a similar manner; Figure 3 represents a rolled capacitor; Figure 4 shows a sectional View of a portion of the electrodes and dielectric sheets of Figure 3; and Figure 5 is a side view of a cable, the casing being partly removed to permit the interior of the parts to be seen.

The transformer illustrated in Figure 1 comprises a casing 1, core 2, coils 3 insulated with manila paper, kraft paper, cotton of other fibrous insulation, insulating and cooling medium 3, lead-in bushings 5, and suitable leads 6 connected to the coil assembly. The insulating and cooling medium may consist of chlorinated biphenyl; trichlorbenzene and tri a thienyl stibine in the following proportions.

Parts by weight Chlorinated biphenyl (60% Cl) 60 Trichlorbenzene 40 Tri a thienyl stibine 0.1

the present invention in the cooling and insu lating liquid will not only substantially reduce the deleterious effect of such liquid on organic insulation but will also greatly reduce the corrosion of the metal parts of the transformer which come in contact therewith in the presence or absence of air.

The switch shown in Figure 2 comprises a casing 6', fixed contacts '1 and 8, and movable contacts 9 and i0 which cooperate therewith. The movable contacts are mounted upon a support H which in turn is operatively connected to actuating levers l2. The following is illustrative of a suitable arc quenching liquid which may be used in this device, it being understood that the invention is not limited thereto.

Parts by weight Chlorinated biphenyl (55% Cl) 'Irichlorbenzene 20 Triphenyl stibine diacetate 0.05

In the operation of electric switches, the unavoidable arcing which accompanies make-andbreak of the switch contacts results in partial decomposition of the chlorinated biphenyl or other halogenated organic compounds. The presence of the organic antimony compounds of the present invention in the above liquid renders the halogen decomposition products innocuous with the result that switches provided therewith are substantially free from the corrosion normally accompanying the use of such devices filled with halogenated organic compounds per se.

The capacitor shown in Figure 3 is made up of alternate layers of metal foil such as aluminum or tin foil separated by sheets of dielectric material. It is produced by interleaving two dielectric sheets, such as linen or kraft paper, with the metal foil, and rolling the interleaved sheets in the conventional manner. The rolled capacitor is then impregnated with the dielectric composition by any suitable process, such as vacuum impregnation, with chlorinated biphenyl having dissolved therein a small proportion of an organic antimony compound such as tri a. thienyl stibine. The capacitor is then placed in a protective case or otherwise used as desired.

The following range of compositions is illustrative of suitable capacitor impregnants:

Composition I Per cent by weight Liquid chlorinated biphenyl, particularly chlorinated biphenyl containing fromv42% to 60% by weight of chlorine O-about Conventional chlorinated organic dielectric materials about l00-0 Organic antimony compounds 0.01-1

Composition II Parts by weight Chlorinated biphenyl (42%-60% Cl) 75 Trichlorbenzene 25 TIi-a thienyl stibine 0.1

Of the above range of compositions, the preferred capacitor impregnant is one having the following composition:

Parts by weight Chlorinated biphenyl (55% C1) 75 Trichlorbenzene 25 TIi-a thienyl stibine 0.1

The presence of organic antimony compounds in chlorinated biphenyl or other halogenated orassasos ganic compounds provides excellent protection against the deleterious action of halogen decomposition products on metal, paper and other organic insulation material and consequently capacitors provided therewith will have a longer useful life and greater dielectric stability than similar capacitors containing halogenated organic compounds per se. Moreover, capacitors containing organic antimony compounds will not exhibit an ever increasing power factor with time when operated at high temperatures and voltages as is typical of capacitors impregnated with halogenated organic materials which are not associated with one of the above corrosion inhibitors.

Figure 4 shows a section of one turn of the finished rolled capacitor illustrating the alternate electrodes and dielectric layers. In accordance with the present invention, the finished capacitor contains a halogenated organic compound, preferably chlorinated biphenyl, and a minor proportion of an organic antimony compound.

The cable of Figure 5 comprises a core l3 cable conductors l4, insulation consisting of paper or other suitable material [5 and a casing IS. The space between the insulated conductors and the casing is filled with a mixture of any of the liquid chlorinated organic compounds and the organic antimony compounds mentioned above. Such a composition may consist of a mixture of the following ingredients, but it is to be clearly understood that the invention is not restricted thereof.

Parts by weight Chlorinated biphenyl (60% C1) 50 Trichlorbenzene V 50 TIl-a thieny1 stibine dibenzoate about 0.1

The experimental data hereinafter presented illustrate in a striking manner the scavenging or corrosion inhibiting action of organic antimony compounds on dielectric compositions, containing halogenated organic compounds. In accordance therewith, the effect of the corrosion inhibitor is brought out by showing and comparing the action of an I-ICl-saturated halogenated dielectric composition, with and without the inhibitor, on organic dielectric materials such as paper; The effectiveness of the inhibitor is manifested by the protection it affords paper against attack by hydrogen chloride and the degree of attack is indicated by the extent to which the tensile strength of the paper is decreased. This willbe rendered more apparent by reference to the following examples.

EXAMPLE I Six strips of manila wrapping paper (6" x 1") were humidified at 65% R. H. at 70 F. for a period of 48 hours and subjected to tensile strength tests. These tests were run on a Scott IP-2 serigraph with a jaw separation of 3- inches and a rate of travel of 34.5 seconds for a load of 40 lbs. The result of these tests, being the average of 6 breaks, was as follows:

Tensile strength of paper samples 46.2 lbs/in.

EXAMPL II Six strips of the same piece of manila wrapping paper were allowed to soak at a temperature of 75 C. for 1%,; hours in an HCl saturated solution consisting of 60 parts'by' weight of chlorinated biphenyl (60% Cl) and. 40 parts by weight of trichlorbenzene and at the end of this operation, the papers were soaked for 15 minutes in benzene, another 15 minutes in methanol and dried. After cutting one half inch from each end of the dried paper strips, they were subjected to the above tensile strength tests with the following result:

Tensile strength of impregnated paper samples 11.5 lbs/in.

These examples demonstrate that l-ICl had a highly deleterious action on the samples since the tensile strength of the paper changed from 46.2 1bs./in. to 11.5 lbs./in., a decrease in tensile strength of approximately EXAMPLE III The foregoing example was repeated using samples of the same paper and the same impregnant except that 0.1 part by weight of tri-a thienyl stibine was added. The tensile strength of the impregnated paper was found to be 39.6 lbs./in., thus demonstrating that the above compound is a highly eifective material for rendering halogen decomposition products such as H01 innocuous to paper or other fibrous organic dielectrics.

EXAMPLE Iv or corrosion inhibitor for halogenated organic compounds as it is superior to tetraphenyl tin, a material used commercially for the above purpose. As evidence of its superiority over tetraphenyl tin, reference it made to the following results of tensile strength tests made with both of these compounds:

lbs./ in.

Tensile strength of untreated paper 46.2 Tensile strength of paper treated with composition consisting of 60 parts by weight of chlorinated biphenyl (60% C1) 40 parts by weight of trichlorbenzene and 0.1 part by weight of tetraphenyl tin Tensile strength of paper treated with composition consisting of 60 parts by weight of chlorinated biphenyl (60% C1) as parts by weight of trichlorbenzene and 0.1 part by Weight of tria thienyl stibine diacetate These tests show that the average tensile strength of the paper samples was reduced from 46.2 lbs/in. to 16 lbs/in. in the case of tetraphenyl tin whereas when tri a thienyl stibine diacetate was employed, the tensile strength was reduced only to 18 lbs./in., thus demonstrating the superior scavenging action of the latter compound.

The following table illustrates the electrical properties of the dielectric composition consisting of 60 parts by weight of chlorinated biphenyl (60% Cl) and 40 parts by weight of trichlorbenzene and also shows the effect thereon of adding. 0.1 part by weight of tri a. thienyl, stibine.

The above experimental data indicate that organic antimony compounds do not impair, but actually improve, the electrical properties of the halogenated organic compounds associated therewith and that, therefore, such compositions are suitable for use in transformers, capacitors, switches, cables and other electrical devices.

The description of the present invention has been directed primarily to compositions containing chlorinated biphenyl, trichlorbenzene and organic antimony compounds, but it is to be understood that the invention is not restricted thereto but embraces halogenated organic compounds generally. Thus, the above organic antimony compounds may be used as stabilizers, scavengers or corrosion inhibitors for chlorinated naphthalene, chlorinated diphenyl ketone, chlorinated diphenyl oxide, chlorinated diphenyl methane, chlorinated diphenyl ethane, chlorinated benzene, chlorinated toluene, chlorinated nitro diphenyl, chlorinated alkylated benzenes, chlorinated alkylated biphenyls, ethyl trichlorbenzene, ethyl tetrachlorbenzene, ethyl pentachlorbenzene, chlorinated terphenyl, chlorinated quarterphenyls, chlorinated parafiinic hydrocarbons, chlorinated alicyclic hydrocarbons, chlorinated oxygen-containing organic compounds, chlorinated rubber, chlorobutadiene polymers, chlorinated fats, chlorinated vegetable oils, chlorinated animal oils, chlorinated mineral oils ormixtures of two or more of these. In place of the chlorinated compounds, the corresponding fluorine, bromine and iodine derivatives may be used. In fact, any halogenated organic compound or composition which tends by reason of its halogen content to cause corrosion of metals or dehydration of paper or organic fibrous insulation, may be rendered substantially innocuous by means of the organic antimony compounds defined by the general formulae set out above.

The method of incorporating the organic antimony compounds varies with the halogenated organic compound or composition. If the compound or composition is liquid at room temperature, the above compounds are merely dissolved therein in suitable concentrations; if it is a solid, the organic antimony compounds are blended therewith by the use of solvents or swelling agents or by means of mixing rolls, etc. In the case of halogenated polymers, the organic antimony compounds may be incorporated before, during or after polymerization of the corresponding monomers.

The quantity of organic antimony compounds used varies with the halogenated organic compound or composition. In general, satisfactory results are obtained by employing these compounds in an amount varying from 0.05% to 1%, and preferably from 0.05% to 0.1% by weight of the halogenated organic compound or composition, but it is to be understood that the invention is not limited thereto as slightly lower and some- ;what higher concentrations may be employed? Stated broadly, the organic antimony compounds may be used in amounts varying from 0.01% by weight up to and above the limit of their solubility in the halogenated organic compound or composition. In most instances, it is desirable not to exceed the solubility limits of the organic antimony compounds, but there are some applications such as heat exchanging operations in which this may be done without harmful effects.

As widely different embodiments of this invention may be made without departing from the spirit thereof, it is to be understood that the invention is not limited to the specific embodiments except as defined in the appended claims.

What I claim is:

1.'A composition of matter consisting essentially of a halogenated aromatic compound and an organic antimony compound selected from the group consisting of Ro-nsbXn and R sbz, wherein R is an organic radical, o is an integer corresponding to the valence of antimony, X is selected from the group consisting of organic and inorganic radicals, n is selected from the values: 0, 1, 2, 3 and 4 and y is selected from the values: 2' and 4, said antimony compound being used in an amount varying from 0.01% by weight up to and above the limit of its solubility in said composition.

2. A composition of matter consisting essen tially ofa chlorinated aromatic compound and an organic antimony compound selected from the group consisting of Ro-nSbXn and Rysbz, wherein R is an organic radical, o is an integer corresponding to the valence of antimony, X is selected from the group consisting of halide, oxide, sulfidefcyanide, thiocyanate, acetate, benzoate, succinate, oxalate and tartrate radicals, n is selected from the group of values consisting of 0, 1, 2, 3 and 4 and y is selected from the group consisting of 2 and 4.

3.A heattransfer and dielectric composition consisting essentially of chlorinated biphenyl and about 0.05% to about 1% by weight of an organic antimony compound as defined in claim 1.

4. An insulating and cooling medium for electric apparatus consisting essentially of a liquid chlorinated biphenyl and about 0.05% to about 1% by weight of an organic antimony compound as defined in claim 2, said chlorinated biphenyl containing froln 42% to by weight of chlorine.

5. A dielectric composition consisting essentially of chlorinated biphenyl and about 0.05% to about 1% by weight of an organic antimony compound as defined in claim 2, said chlorinated biphenyl containing from 42% to 60% by weight of chlorine.

6. The composition defined in claim 5 wherein tri a thienyl stibine is the organic antimony compound employed.

7. The composition defined in claim 5 wherein triphenyl stibine diacetate is the organic antimony compound employed.

8. The composition defined in claim 5 wherein tri a. thienyl stibine dibenzoate is the organic antimony compound employed.

9. A heat transfer and dielectric composition consisting essentially of chlorinated biphenyl and as a Scavenger therefor about 0.05% to about 1% by weight of trl-c-thienyl stibine.

10. A heat transfer and dielectric composition consisting essentially of chlorinated biphenyl and as a scavenger therefor about 0.05% to about 1% v by weight of triphenyl stibine diacetate.

11. A heat transfer and dielectric composition 9 consisting essentially of chlorinated biphenyl and as a scavenger therefor about 0.05% to about 1% by weight of tri-a-thienyl stibine dibenzoate.

12. An insulating and cooling composition for electrical apparatus consisting essentially of a liquid chlorinated biphenyl and about 0.05% to about 0.1% by weight of an organic antimony compound selected from the group consisting of Rv-nsbxn and Basin, wherein R is an organic radical, '0 is an integer corresponding to the valence of antimony, X is selected from the group consisting of organic and inorganic radicals, n is selected from the values: 0, 1, 2, 3 and 4 and y is selected from the values: 2 and 4.

13. An insulating and cooling composition consisting of about 60% by weight of chlorinated biphenyl, about 40% by weight of trichlorbenzene and about 0.1% by weight of tri-a-thienyl stibine.

14. An electric arc quenching composition consisting of about 80% by weight of chlorinated biphenyl, about 20% by weight of trichlorbenzene and about 0.05% by weight of triphenyl stibine diacetate.

15. A capacitor impregnant having substantially the following composition.

An antimony compound selected from the group consisting of Rv-nsbxn and R Sba wherein R is an organic radical, v is an integer corresponding to the valence of antimony, X is selected from the group consisting of organic and inorganic radicals, n is selected from the values: 0, 1, 2, 3 and 4 and y is selected from the values: 2 and 4. 16. A capacitor impregnant consisting of about 75% by weight of chlorinated biphenyl (42 %-60% Cl) about 25% by weight of trichlorbenzene and about 0.1% by weight of tri-athienyl stibine.

RUSSELL L. JENKINS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,041,594 Clark May 19, 1936 2,177,561 Cook Oct. 24, 1939 2,181,915 Rosen Dec, 5, 1939 2,257,150 Lincoln et a1. Oct. 7, 1941 2,339,091 McLean Jan. 11, 1944 2,453,493 Clark et a1. Nov. 9, 1948 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF A HALOGENATED AROMATIC COMPOUND AND AN ROGANIC ANTIMONY COMPOUND SELECTED FROM THE GROUP CONSISTING OF RV-NSBXN AND RYSB2, WHEREIN R IS AN ORGANIC RADICAL, V IS AN INTEGER CORRESPONDING TO THE VALENCE OF ANTIMONY, X IS SELECTED FROM THE GROUP CONSISTING OF ORGAIC AND INORGANIC RADICALS, N IS SELECTED FROM THE VALUES: 0,1,2,3 AND 4 AND Y IS SELECTED FROM THE VALUES: 2 AND 4, SAID ANTIMONY COMPOUND BEING USED IN AN AMOUNT VARYING FROM 0.01% BY WEIGHT UP TO AN ABOVE THE LIMITE OF ITS SOLUBILITY IN SAID COMPOSITION. 